In the molding art, and particularly in large injection molds, there can be a problem of mold centering because the pressures imparted within relatively large mold chambers by the molding compound as it flows in can cause a small temporary warpage of even large steel molds. Additionally, slight misalignments of the mold cavity and the mold core may take place, all of which may cause errors in the dimensioning of the products molded therein.
To account for this, in the prior art, molds utilize various mating shoulders and recesses respectively in the mold core and mold cavity which assist in the centering of the core and cavity in their exact, desired transverse position relative to each other.
In one prior art embodiment, a portion of the mold cavity is positioned in the closed position, inside of a retaining portion of the mold core so that the mold core resists expansion of the mold cavity due to pressure in the molding chamber, and to improve the centering of the core and cavity. However, at the abutting, lateral faces of these two portions, a significant amount of wear can take place, especially when the core and cavity are opened while the mold chamber remains pressurized. Eventually, this wear must be repaired.
In another design of centering system for an injection mold, an adjustably advanceable ring is carried on the mold core, to retain an inner portion of the mold cavity to prevent its expansion and to assist in its centering. As the ring wears, it may be advanced to account for the wear and reused. However, because the ring is advanceable, there must be a certain amount of loose fitting of the ring in the recess of the mold core where it resides. Thus, such an area does not assist significantly in the sealing against the formation of thin flashing of molding compound, so that the quality of the products manufactured therein may suffer.
In accordance with this invention a mold is provided, typically an injection mold, in which good alignment between the core and cavity may be achieved, while the resulting wear resulting from such good alignment may be "focused" onto an inexpensive, easily replaceable wear member. Thus, when the wear member has worn to an excessive degree, it may simply be replaced with little difficulty and time. Additionally, the wear member may be a relatively simple, soft metal ring of low cost.